| 摘要 |
An optical processing and correlation system is described in which each user is assigned a unique code as its identity. When a user wishes to establish a communication link with another user, it encodes the unique identity of the latter (representing the destination address) and broadcasts to all other users. On reception, each receiver correlates its own unique address with the received signal. If the received signal has arrived at the correct destination, then the correlator output is a maximum; this is known as auto-correlation. Alternatively, if the received signal arrives at an incorrect destination, the correlator output is a minimum, known as cross-correlation. Thus, by monitoring the correlator output, desired and undesired signals can be identified by an all-optical network. Various embodiments of the invention are described. In one aspect of the optical processing arrangement of the present invention, each raw data or information data bit, is coded into one period of a code sequence according to the following rules: (a) if the data is "1", it is coded into a code sequence x. (b) If the data is "0", it is coded into a code sequence x &cir& NOt . The generated code sequences (x or x &cir& NOt ) has a further coding stage. Each "1" in the sequence x (or x &cir& NOt ) is translated to two bits separated by time T; for example (01) or (10). Each zero is translated into a complementary pair, that is (10) or (01), respectively, in a preferred arrangement each "1" is translated into (01) and each "0" is translated into (10). A "0" signifies no light pulse whilst a "1" signifies the presence of a light pulse. The digits of (01) or (10) are separated by the time T. |
